If they're Cordyline they'll by now have developed woody stems (if not, these are Phormiums). You can cut Cordyline down and they will regrow - this is usually done in early summer, but as you're in Zone 10, you can probably do it now, though it might not entirely correct the problem - if your plant is leaning over, it's loose at the roots, and that will need putting right. You will also need to cut both plants down to keep the symmetry in the planting arrangement shown, and be aware that you will get many 'plantlets' growing out of the remaining stem or off the roots, some of which you may want to remove as time goes by.